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    <meta charset="UTF-8">
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    <title>Document</title>
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    <math xmlns="http://www.w3.org/1998/Math/MathML">
      <mrow>
        <msup><mi>a</mi><mn>2</mn></msup>
        <mo>+</mo>
        <msup><mi>b</mi><mn>2</mn></msup>
        <mo>=</mo>
        <msup><mi>c</mi><mn>2</mn></msup>
      </mrow>
    </math>
    <pre>
        var a = 1;
        console.log(a);
        function fn(){
            
        }
    </pre>
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